Dear folks
I imagine someone sooner or later is going to point out that the star which
is truly the nearest neighbour to the Solar System is in fact Proxima
Centauri, one of a group of three stars of which Alpha is the largest. The
actual distance is 4.22 light year.
I accept of course that it's the use of non SI that was really the point of
the exercise. Astronomers do use a variety of special units not listed in
SI:
asronomical unit (AU)
parsec
solar mass
bolometric, photometric magnitude ...
I dare say most of these can be replaced with equivalent SI but I think we
come up against it with mass.
The Sun has a mass of 2E30 kg or 2 000 000 000 Yg. It gets a bit hairy when
we start to measure the masses of galaxies of which our own is 2E11 solar
masses!
Phil Hall
----- Original Message -----
From: "Linda D. Bergeron" <[EMAIL PROTECTED]>
To: "U.S. Metric Association" <[email protected]>
Sent: Sunday, February 12, 2006 2:00 PM
Subject: [USMA:36018] Re: Metrication matters 32 and Metrication matters 33
I have current sources that list both 4.2 and 4.3 for the distance to Alpha
Centauri, depending on which one I choose to use.
In either case the difference between the two figures only comes down to
less then one petameter. A difference that is only going to matter to a
project engineer at NASA or the European Space Agency.
Besides the point of the whole statement was the continued use of non-SI
units in some areas of science and the confusion that this can lead to.
So Pat, keep up the good work!
Linda D. Bergeron
----Original Message Follows----
From: "James J. Wentworth" <[EMAIL PROTECTED]>
Reply-To: [EMAIL PROTECTED]
To: "U.S. Metric Association" <[email protected]>
Subject: [USMA:36017] Re: Metrication matters 32 and Metrication matters
33
Date: Sun, 12 Feb 2006 02:20:03 -0900
The Alpha Centauri stellar system is described in all of the books and
articles I've read as being 4.3 light years away, not 4.2 light years. --
Jason
----- Original Message ----- From: "Philip S Hall" <[EMAIL PROTECTED]>
To: "U.S. Metric Association" <[email protected]>
Sent: Sunday, February 12, 2006 2:08 AM
Subject: [USMA:36016] Re: Metrication matters 32 and Metrication matters
33
Dear Pat
Thanks for notifyinmg us of your newsletter - very interesting, especially
the piece on energy units. I think your long list makes the point very
effectively as to why it's important to phase out obsolete and unnecssary
units of measurement. Global warming is an important issue and one that
suffers a great deal from poor understanding by those with the power to
change things.
A couple of minor points:
The URL needs to be http://www.metricationmatters.com/newsletter i.e. it
doesn't work without the www in front (or it didn't for me)
In section 3 Oddities you've got "The nearest star to the Earth is 4.2
light years away"
That's a popular trick question - the correct is answer is about 150
gigametre. I refer of course to the Sun.
BTW there is another point I'd add to your discussion in that section. Why
do people keep on quoting interplanetary distances in billions of km?
(when they're not using the pathetically inadequate mile that is) What's
wrong with Mm, Gm, Tm etc? I think it's a hang-over from old pre-metric
habits where they had nothing bigger than a mile (or league maybe) which
are only suitable for terrestrial distances.
Regards
Phil Hall
----- Original Message ----- From: "Pat Naughtin"
<[EMAIL PROTECTED]>
To: "U.S. Metric Association" <[email protected]>
Sent: Sunday, February 12, 2006 9:39 AM
Subject: [USMA:36015] Metrication matters 32 and Metrication matters 33
Dear All,
For those of you who like to read the 'Metrication matters' newsletter on
the web, it is now at http://metricationmatters.com/newsletter down near
the
bottom with all of the other back copies of 'Metrication matters'.
I just realised that I made a mistake and forgot to post last month's
'Metrication matters 32' so I have fixed this error and both 'Metrication
matters 32' and 'Metrication matters 33' are now on the same web page at:
http://metricationmatters.newsletter
Cheers,
Pat Naughtin
PO Box 305, Belmont, Geelong, Australia
Phone 61 3 5241 2008
Pat Naughtin is the editor of the free online monthly newsletter,
'Metrication matters'.
You can subscribe by going to
http://www.metricationmatters.com/newsletter
Pat is the editor of the 'Numbers and measurement' chapter of the
Australian
Government Publishing Service 'Style manual for writers, editors and
printers'. He is a Member of the National Speakers Association of
Australia
and the International Federation of Professional Speakers. He is also
recognised as a Lifetime Certified Advanced Metrication Specialist
(LCAMS)
with the United States Metric Association. For more information go to:
http://metricationmatters.com
This email and its attachments are for the sole use of the addressee and
may
contain information that is confidential and/or legally privileged. This
email and its attachments are subject to copyright and should not be
partly
or wholly reproduced without the consent of the copyright owner. Any
unauthorised use of disclosure of this email or its attachments is
prohibited. If you receive this email in error, please immediately delete
it
from your system and notify the sender by return email.
--
_________________________________________________________________
Is your PC infected? Get a FREE online computer virus scan from McAfee®
Security. http://clinic.mcafee.com/clinic/ibuy/campaign.asp?cid=3963
